Manufacture of a vanillin and 3-ethoxy-4-hydroxybenzaldehyde



' auANUEAQTURu or A useums; s muoxY- i-HYDRQXYBENZAL E YDE I I j NoDrawing. erialjiqoq and in German yilanuary 26, 1931. i 1 Y PatentedAug. 23, 1932 non]? .PFANNEN'STIEL; or IBERLIINTLICHTENRKDELGERMANY;ASSIGNOR T03 win I manor CHEMIGALiCOMPANI'ING;OF;'1\TEW YQRK, NJYCQBBOBATION or New T YORK 4* My presentinyention relates to'a newprocess of manufacturing 3-methoxy-fl-hydrbxy{ b'enzaldehyde (vanillin)and 3 '-jethoxy-4-hydroxybenzaldehyde. 3:.

3 methoxyA hydroxyphenyltrichlor ineth- 'ylcarbinol (trichlormethylgu'aiacylcarbinol) which is 'easily accessible (cf. Berichte derDeutschen ,Chemis'chen' Ge'sells'chaft, yoll 56, page 982) alreadyhasbeen suggested to be used as a startin'g'm aterial in the manufac tureof vanillin As described in U. SyPatent No. 1,536,732,in accordance withSavariau (Chemisches Zentralblatt, 1908 1, page q 1388) the saidcarbinol behaves quite differently from phenyltrichlormethylcarbinol;

whereas the latter, when boiled with potas- 1 sium.carbonate, isdecomposed so as to form benzaldehyde' and chloroform; the 3-1neth' yhyyP e y trich fm hyl r' nol I: when treated iu"thfesame'manner, does not;

show even the slightest formation of i/fanillin and chloroform.Thisprocess could; there fore, not bexused for preparing vanillin, so'that-it wasnece'ssa'ry tdadopt thej more complicated and tuipensiVe-'oxidation method which is the object of'UI'S; Patent'N 0; 1,536,- 7 32.y I

According to thisjinvention, 3-methoxy-4- go hydroxybenzaldehyde and3-ethoxy-4-hydroxybenzaldehyde are/obtainable with a good yield bytreating 3=methoxy-4-hydroxytrichlormethylcarbinol' or3-ethoxy-4-hydroxytrichlormethylcarbinol with an alkali metal alcoholateor an alcoholic solution of an I alkali metal hydroxide or analkaline-earth metal hydroxide. A strong reaction is produced by whichthe corresponding yanillin salt is obtained, whichon acidificationyields free vanillinor 3-ethoxy-4-hydroxybenzalde hycle respectively ina Very good yield. This smooth reaction, certainly, could not gbeforeseen, since3-methoxyand S-ethQXy-AFhydroxytrichlormethylcarbinol areknown be a particularly sensible on account of their par-'- ticularsubstitution. If; nevertheless; there- ;actibil takesa favorable c ouise,this'is probably due to the acid nature of 'the hydroxy group whichallows a" stable alkali'salt to be, formed?" The reactio'n 'now takesplace with;

ivaifillin the reaction probably takes place cording-to the followingscheme:

1 Ifthe reaction 'is' condu ted within-aquaoust alkali the glycide-likecompound'repi'e-' sented in' Formula IIis e v'identl'yinot' formed. a Inthiscase, uncontrollable reactions lead to dark-browh' smearsi i Thefollowing examples illustrate the in vention without limiting it to thespecific def tails given therein, the parts being by weight 2 Example LA "solution of 271.5 .parts of 35rnethoxyit-hydroxyphenyltrichlormethylV V carbinoli( about iu240 p'a-rts of'ui'etha:

n01. isadded'to a solution of 69 partso i sodi-j um 'isQAOO parts ofmethanol. The solution is boiledinarefluxapparatus for hours 90 andacidified with sulfuric acid or another mineral acid; the methanol isthen expelled by means of steam and the solution isexhaustivelylextracted with chloroform. On distillation in a vacuum, 84parts, that is 60% of the theory, of vanillin are obtained, boiling at 1to 145 C. under 6 mm. pressure.

Example 2.-A solution of 271.5 parts of 3-methoxy4-hydroxyphenyltrichlormethylcarlution 'of 270 parts of potassiumhydroxide (90%'strength) in650 parts of ethanol. By the reaction heatevolved the solution which the beginning has-a temperature of 20 C.

of 1 hours. After the reaction has ceased, the whole is kept boiling foranotherl/ hour and the;product is .workedup. as. indicated in Example 1.The vacuum distillation yields 6'9par ts (corresponding to 16%ofthetheory of Vanillin boiling at 145 to 152 C. under 6.5 mm. pressure.Y

; Emrtmplafi- A solution of 271.5 partsof 3'-Inethoxy-4-hydroxyphenyltrichlormethylcarbinol ill 480 parts of methanolis added at a temperature of about 20 (Ito a solution of 27 0 partsofpotassium hydroxide in 480 parts of methanol. The reaction immediatelysets in with violent boiling; after it has ceased boiling is continuedfor a further hour in a refluxflapparatus. When working up the reactionproduct asindicated in Example 1, there are obtained 101' parts (66percent of the theory) of vanillin boiling at'145 to 150 C. under 5.5 to6.5 mm. pressure.

E mample .{.A solution of 271.5 parts of 3 methoxy-4-hydroxyphenyltrichlormethylcarbinolin 240 parts of methanol isintroduced, drop by drop, into a boiling solution of 4550 parts ofanhydrous barium hydroxide in 2000 parts of methanol and the whole isboiled for 6 hours in a -refluxapparatus. After acidification withsulfuric acid, the solid matter is separated by filtration and theremaining solution is worked up as indicated in Example 1. There areobtained 96 parts (63 per cent of the theory) of vanillin boil ing at145 to 149 C. under 6 mm. pressure.

In a completely analogous manner 3- ethoxyl-hydroxybenzaldehyde may beproduced when starting from 3-ethoxy-4-hy droxytrichlormethylcarbinol asseen from the following example.

Example 5.A solution of 285.5 parts of 3- ethoxy 4hydroxyphenyltrichlormethylcar binol containing per cent of puresubstance in 400. parts of methanol is run within 30 'minutes into.aboilingsolution of 375 parts of potassium hydroxide containing 90 percent of KOH in 1200 parts of methanol.

Boiling'is cont'nued for anotherthree hours in arefluxapparatus,.whereafter the solution is acidified with a dilute mineralacid and exhaustively extracted with chloroform. By.

distilling under reduced pressure there are binol in 650 parts ofethanol is added to a soamp S eh t boil ngi mpemtu e in theco r e.

obtained 118 parts of 3-ethoxy4-hydroxybenzaldehyde corresponding to 72per cent of the theory.

In the place of the potassium hydroxide the equivalent quantity ofsodium hydroxide or an alkali earth metal hydroxide or of a mixture ofsodium hydroxide and potassium hydroxide may be utilized with the samegood result. This may be seen from the following ex- 6.-271.5 parts of 3methoxy-4;-

(the

"Example hydroxyphenyltrichlormethylcarbinol .rawI. product asobtainable. by condensing pguaiaoolwith chloral and'containing about 90%of the said carbinol) are dissolved in about 500 parts of methanol and asolution 1 of 180 parts ofsodium hydroxide (90%) and potassium hydroxide(90%) in 2500 parts of methanol is slowly added. The reaction isperformed. as described-in the foregoing examples. Whenworking upthereaction mixture in the manner described, 112 parts of vanillin areobtained.

1. The. process. which comprises treating an alkoxyhydroxyphenyltrichlormethylcarbinol ofthe general formula:

wherein X; eans methyl or ethyl, with. a saponifying-agent of the groupconsistingof alkali metal alcoholates' and alcoholic solutions of alkalimetal hydroxides and alkaline-earth metal hydroxides, and acidifying thereaction mixture.

2. The process which comprises treating analkoxyhydroxyphenyltrichlormethylcarbinol of the general formula:

an alcoholic solutionof 3-ethoxy-4-hydroxytrichlormethylcarbinol withpotassium hydroxide of about 90 per cent strength dissolved in methanol,and acidifyingthe reacti-on mixture. 7 1

5. The process which comprises treating an alcoholic solution of3-methoxy-4-hydroxytrichlormethylcarbinol with a mixture of potassiumhydroxide and sodium hydroxide of about 90 per cent strengthdissolved-in acidifying the reactionmixmethanol, and

ture; y

In testimony whereof I afiix my signature.

ADOLF PFANNEN STIEL.

